The proliferative capacity of committed T-lymphocyte precursor cells (CFU-T1) from patients undergoing bone marrow transplantation is being examined. Thirty-one patients have been transplanted as treatment for leukemia. Thirteen have received concomitant cyclosporin A (CyA). The effect of CyA treatment on marrow engraftment with regard to CFU-T1 proliferation is being measured. Thirteen CyA-treated and nontreated patients can be closely matched with regard to disease, sex, and incidence of graft-versus-host (GVH) reaction. We will compare these two groups with regard to CFU-T1 proliferative capacity by following T-colony formation in soft agar culture as a function of time from transplant. Most of these patients are more than one year post-transplant. Prostaglandin E (PGE), which is known to modulate CFU-T1, has been measured by radioimmunoassay in the cell cultures of these patients. We will seek correlations between PGE levels and T-colony number as well as with the incidence of GVH. In separate in vitro studies, we are examining the effects of PGE and Interleukin 2 (IL-2) on T-cell growth. The effects of various cyclooxygenase and lipoxygenase products on an IL-2 dependent T-cell line (CTLL-1) will be measured. The interaction of arachidonate metabolites, CyA, and IL-2 will be assessed through cell cycle kinetic analyses. We seek greater insight into the mechanisms of these agents in modulating T-cell ontogeny during marrow engraftment. (LB)